The present invention relates to a mechanism for tilting an outboard motor about a horizontal axis relative to its mounting bracket and the boat transom and, more particularly, to a locking apparatus for the tilt mechanism for preventing inadvertent displacement of the outboard motor from its upper most trailering position.
U.S. Pat. Nos. 4,331,430 and 4,472,148 and 4,826,459, all of which are assigned to the assignee of the present invention, describe similar mechanisms for providing a variety of outboard motor tilt positions. The positions typically include a series of lower trim positions, including one or more shallow water drive positions, and an uppermost trailering position. These patents and the pending application describe alternate mechanisms for selecting and establishing the various tilt positions and moving the motor between them. In particular, U.S. Pat. No. 4,472,148 discloses a mechanism which allows the operator to change positions simply by pushing down on the motor tiller handle and tilting the engine up. A ratchet mechanism allows stepwise movement between a trim pin and serially arranged position notches to allow the motor to be tilted from the original down position to any higher position, including the uppermost trailering position, without activating any supplemental mechanism. To bring the motor back down to the original position, and depending upon which upper position it has been temporarily moved to, the motor is tilted up to and slightly beyond the uppermost shallow water drive position or the top trailering position, and released. The trim pin follows a return path in a closed circuit cam track that returns the trim pin and motor to its original position as the engine tilts down.
Although the mechanism of U.S. Pat. No. 4,472,148, as well as those of the other prior art mechanisms identified above, has operated satisfactorily, it has been found that in some situations the motor may be inadvertently dislodged from its uppermost trailering position. For example, where the outboard motor is used as an auxiliary engine and is in its trailering position because the main drive unit is being used, the pounding from heavy seas or high wave action may cause the motor to become dislodged and dropped from its trailering position. Likewise, when the motor is being trailered in its full up trailering position, jarring of the trailer as it travels over a road or ground surface may also cause the motor to be disengaged from the trailering position. In either situation, inadvertent disengagement from the trailering position will allow the motor to drop about its tilt axis resulting in possible damage to the motor.
It would be desirable, therefore, to have a manually operable lock mechanism by which the motor could be locked in its uppermost trailering position in a simple, but reliable, manner. In addition, such a lock mechanism would most desirably be able to be incorporated into an existing outboard motor tilt mechanism without major modifications or redesign, and without affecting its operation.